Valve mechanism for rock drills



Oct. 7'-, 1930. ,w. A. SMITH, JR 1,777,775 VALVE MECHANISM FOR ROCK DRILLS Filed Nov. 22, 192e INVENToR.

BY l a u FI HLS ATTORNEY;

ber C is effected through front inlet passages also leading from the opposite ends of the valve chamber Z and from the rearward side thereof through the plate b and through the cylinder B to the front end of the piston chamber C. The passages j and 7c are preferably so arranged that their inlet openings lie substantially in the same longitudinal plane. This is also the preferred arrange-- mentof adjacent grooves g and la which, as will be observed, encircle or surround the inlet openings of the passages j and 7c.

The distribution of pressure fluid to the piston chamber C is effected in this instance by a pair of oscillatory plate valves 0 disposed in the valve chamber (Z in such manner that their free ends oscillate between the passages j and la which they control. The valves 0 have rearward and forward pressure areas p and Q which converge toward the outer free ends of the valves.

As a preferred arrangement the valves are disposed end to end and carry at their inner or adjacent ends lateral trunnions 1 which extend into notches or pockets s in the plate c to serve as pivots for the valves 0 and for holding the valves 0 against endwise movement in the valve chamber (l.

lhen adapted for use in rock drills employing rifle bars as in the present instance and where it may be desirable to dispose the valves in the same transverse plane, said valves may be provided with suitable recesses z? which combine to form a cylindrical aperture for the reception of the rifle bar and, as in the present instance, a bushing which encircles the rifle bar and extends into the plates b and c for preventing leakage of pressure fluid from the valve chamber along the rifle bar into the piston chamber C. y

The ends of the valves o carrying the trunnions r are preferably of a thickness substantially equal to the depth of the valve chamber d in order to divide the said valve chamber d into two pressure chambers c from each one of which lead a pair of inlet passages j and la. By dividing the valve chamber d into separate pressure chambers, each valve may act independently of the other and without being influenced by any variation in pressure which may exist in opposite ends of the valve chamber d.

The operation of the device is as follows: By rotating the throttle valve O to the open position illustrated, pressure fluid will flow through the passage S into the supply reservoir T, thence into the supply passages c and f to the rearward and front sides of the,

valve chamber d.

Assuming the piston to be in the position illustrated, pressure fluid fiowing into the grooves L will pass through the rearward inlet passages 7' into the rearward end of the piston chamber C to impel the piston D for wardly against the working implement.

After the free exhaust port E is covered by the piston D, the air in the front end of the piston chamber C will be compressed and will flow through the inlet passages 7c to act against the rearward pressure surfaces p of the valves o.

Inasmuch that the rearward pressure surfaces p are exposed to pressure over a smaller area than the pressure surfaces g, the valves o will remain in the rearward positions until the piston D uncovers the free exhaustport E. The pressure fluid in the rearward end of the piston chamber C will then be exhausted to the atmosphere and as a result the pressure acting against the pressure areas g will drop considerably below line pressure. l/Vhen this drop in pressure in the forward side of the valve chamber cl takes place, the compression, together with the live pressure fluid acting against the rearward pressure y a areas will throw the valves forwardly to cut olf communication between the grooves le, and the rearward inlet passages j.

After the valves o have been thus reversed, pressure fluid will flow from the groove g over the rearward pressure areas 2J of the valves into and through the inlet passages 7u to the forward enolof the piston` chamber C to drive the piston D rearwardly to its initial position;

Y During the rearward stroke of the piston D, the air compressed in the rearward end of the piston chamber C will flow through the inlet passages j to act against the pressure areas Q of the valves 0. l/Vhen the piston D reaches a position in which the free exhaust port E will be uncovered the pressure fluid in the front end of the piston chamber will be exhausted to the atmosphere and the pressure acting against the forward pressure surface g, such as the live pressure fluid in the grooves /L- and the compression in the inlet passages j, will again reverse the valves, thus completing the cycle of operations.

From theforegoing description it will be observed that the valves o will move simultan-eously in the same direction and that the valves are not actuated by the force of suction of pressure fluid flowing over any portions of the valves but by positive pressure acting against the pressure areas both for throwing the valves and for holdineV them in the seated positions. This is a highly advantageous feature in valves of the oscillatory plate type since it assures a steady action thereof. It precludes the possibility of trembling of the valves on their seats and therefore prevents the admission of pressure fluid into the pressure chamber in advance of the piston and as a result a full and heavy blow will be struck against theworking implement by the piston. This invention also assures an abundant and immediate supply of pressure fluid to both ends of the piston chamber for actuating the piston since, immediately upon the opening of the valve, pressure fluid will be uniformly distributed over the pressure y surface ofthe piston. This results in an increased piston speedjand therefore a -drilling efficiency.

I claim:

l. In a fluid actuated rock drill, the combination of a cylinder and a piston, an eX- haust port in the cylinder controlled 'by-'the piston, la valve chest for the cylinder having a valve chamber, inlet passages leading from Y the opposite sides of one end of the valve chamber to the rearward end of the cylinder7 inlet passages leading from the opposite sides ofthe valve chamber to the front end of the `cylinderfa plurality of valves in the valve chamber to control the inlet passages` and `havingfopposed. pressure areas, and `front and rear supply passages leading to the front haustport in the cylinder controlled by the piston, a valve chestfor the 'cylinder having and rear ends of thevalve chamber and constantly-l conveying pressure fluid into the valve chamber to act against thecpposed pressure areas for actuating the valves.

greater `sages leading from the same end of the valve chamber wherewith the supply passages co1ni municate.

In testimony whereof I have signed this specification.

2. Ina fluid actuated rock drill, theA com-` bination of a cylinder and a piston, an eX- a valve chamber, inlet passages leading from th-e opposite sides ofcone end ofthe valve chamber to the rearward end of the cylinder,

l inletpassages leading-from the opposite sides of the other end ofthe valve chamber to the front end of the cylinder, a plurality of oscillatory plate valves in the valvechamber to control the inlet passages, trunnions on the ends of the valves seated in the valve chest to act as pivots for the valves, and rear and piston', a valve chest for the cylinder having a valve chamber, a rearward and a front 1n-j let passage leading from each side of the valve chamber and from opposite ends thereof, to thecylinder, a pair of oscillatory plate valves in the valve chamber to control the i inlet passages and having enlarged adjacent ends to `divide the valve chamber into a pair of pressure chambers, trunmons on the enlarged ends of the valves seated in the valve chestto act as pivotsfor the valves, and. front and rear supply passages leading to` the front and rear ends of the valve chamber constantly conveying pressure fluid into the pressure chambers to act against opposite sides of the valves for actuating the valves and to supply pressure fluid to the inlet pas- WILLIAM A; sMrrH, JR.

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